Drying of peaches by a combination of convective and microwave methods

Abstract

The aim of this work is to study a method to extend the storage life of peaches reducing energy and time consumption and ensuring food quality. The conventional method of hot air dying presents many drawbacks, whereas the microwave drying usually leads to overheating and textural damage. Thus, in this work, a combination of convective and microwave methods, more specifically a two-stage drying process with an initial convective air drying followed by a microwave drying (microwave finishing), was studied for the drying of peaches. Peaches dried at 70 C for various times, 200, 278, 355, 433, and 510 min, were then dried in a microwave oven at powers of 300, 500, and 800 W. Drying rates were examined, whereas dry peaches were characterized for their color, antioxidant capacity, shrinkage, and rehydration ability under optimized conditions for the situations with and without pretreatment with ascorbic acid. Mass transfer of water was described by nine empirical models and by the diffusional approach. The shrinkage of peach tissue during microwave finishing was evaluated and diffusion coefficients were assessed with shrinkage considered. The microwave finishing reduced the drying time by 89 ± 40%, while a smaller shrinkage was observed, with better rehydration characteristics. Practical applicationsPeaches are important commodities in terms of global agricultural production. As peach is a perishable product with a short shelf-life, the food industry has been forced to find methods, such as drying, that extend its storage life by months. The conventional method of hot air dying presents many disadvantages. Last decades, microwave drying proposed an alternative way to improve the quality of dehydrated products. However, microwave is rarely used alone as a drying method and is usually combined with other drying techniques. The main goal of this work is to study an innovative method to extend the storage life of peaches reducing energy and time consumption and ensuring food quality.

Microwave-Assisted Hot Air Drying of Orange Snacks: Drying Kinetics, Thin Layer Modeling, Quality Attributes, and Phenolic Profiles

“…In particular, the integration of microwave pretreatment followed by hot air drying has been investigated in several studies on fruit and vegetables. Tese studies have consistently shown that this combined approach results in reduced drying times while maintaining high product quality, characterized by improved visual appeal and reduced nutrient degradation [17,21,30,37,38]. Terefore, the selection of an optimal drying temperature range between 60 and 80 °C was assumed to reduce processing time while maintaining quality attributes.…”

“…Additionally, microwave drying has the advantage of preserving the quality characteristics of the products including color, vitamins, minerals, and nutritional components [16]. However, microwave drying has some undesirable adverse efects due to overheating, thus textural damage on the fnal product can occur [17]. Tose features result in limited application of the method.…”

“…Te limitations associated with applications of hot air and microwave drying methods alone can be efectively solved by taking advantage of their combined applications. A dual-stage drying approach consisting of convective air drying and microwave drying has been demonstrated to enhance product quality while reducing both time and energy consumption [17,18]. Convective air drying primarily targets surface water removal, whereas microwave energy facilitates the extraction of internal moisture content [19].…”

Effect of Refractance Window™ and oven drying on physicochemical and sensory properties of peach (Prunus persica L.) surplus

“…To preserve the physical, chemical, and sensory properties of peaches, various technologies and drying methods have been employed. Chatzilia et al ( 11 ) and Roknul Azam et al ( 12 ) combined hot-air convection and microwave drying. Pieniazek and Messina ( 13 ) utilized freeze-drying, while Lyu et al ( 14 ) and Zhang et al ( 15 ) initiated the process with osmotic dehydration, followed by infrared pre-drying, and concluded with explosion puffing.…”

“…Currently, there is a trend toward using improved drying methods that are faster, more uniform, hygienic, and require less energy than conventional methods ( 11 , 12 ). However, the selection of a suitable drying technology is a challenging task because fruits and vegetables are susceptible to heating; conductive hydro-drying, such as Refractance Window Drying (RWD), is a novel fourth generation of drying methods with a relatively short processing time, low energy, low cost, scalability, and improved product quality ( 19–22 ).…”